1. Field of the Invention
The present invention relates to a method for producing an alkanolamine by the reaction of ammonia with an alkylene oxide by the use of a microporous material as a catalyst, and an apparatus thereof. Particularly The present invention relates to a method for selectively producing dialkanolamine and an apparatus thereof. More particularly, it relates to a method for producing an alkanolamine by combining the regenerating process of the deactivated catalyst and the process of allowing ammonia to react with an alkylene oxide, and the apparatus therefor.
2. Description of the Related Art
A method of producing ethanolamines by allowing ethylene oxide to react with aqueous ammonia (the concentration of ammonia: 20-40% by weight) is industrially adopted as a method of producing alkanolamines by amination of alkylene oxides with ammonia. In the method, three types of alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine are produced. However, since the demand for the trietanolamine decreases, it is necessary that the production of trietanolamine be suppressed. For this reason, the reaction is typically carried out at a molar ratio of ammonia to ethylene oxides of about 3 to 5 by use of a large excess of ammonia, but the selectivity to trietanolamine is still 10-20% by weight or more.
On the other hand, an alkylene oxide hardly reacts with ammonia in the system where water does not exist. Accordingly, a catalyst is indispensable for such a reaction. For instance, homogeneous catalysts such as organic acids, inorganic acids, and ammonium salts; ion-exchange resins having a sulfonic acid group fixed therein, acid-activated clay catalysts, various zeolite catalysts, and rare-earth-element-carrying catalysts are proposed. However, the purpose of these catalysts is to highly selectively produce monoalkanolamines, and to produce dialkanolamines, the demand of which increases in recent years, is still insufficient.
A catalyst with a high selectivity to dialkanolamines can be produced by using a catalyst which is a microporous material having an effective pore size of 0.45-0.8 nm, or such a microporous material which was ion-exchanged and/or surface-treated.
In the case where dialkanolamines are required to be produced in a still higher selectivity by use of these catalysts, the dialkanolamine can be increasingly produced by separating the produced monoalkanolamine and then recycling part thereof to the reaction system.
When a microporous material is used as the catalyst, the activity of the catalyst may decrease at a comparatively short time. It has never been known so far that the reduction in the activity occurs in producing the alkanolamine. Because the catalyst is expensive, it should not be thrown away after one use, but it should be practically reused in some way. However, the specific apparatus and method for the reaction, which can be industrially advantageously used, have never been known yet.
We have vigorously studied for solving the above problems. As a result, we have found that the deactivated catalyst can be regenerated and have achieved this invention.
In addition, we have found that by alternately repeating a regenerating process of the deactivated catalyst and a process of allowing ammonia to react with an alkylene oxide, a desired alkanolamine can be produced while the regenerating process is being done and an apparatus therefor. We have completed the invention.
An object of the present invention is therefore to provide a method for regenerating the deactivated catalyst.
Another object of the present invention is to provide a method for producing an alkanolamine while the deactivated catalyst is being regenerated.
Still another object of the present invention is to provide an apparatus for producing an alkanolamine while the deactivated catalyst is being regenerated.
More specifically, the object of the present invention is attained by a method of producing an alkanolamine by alternately repeating a regenerating process of the deactivated catalyst and a process of allowing ammonia to react with an alkylene oxide, in producing the alkanolamine by allowing ammonia to react with the alkylene oxide by use of a microporous material as the catalyst.
Moreover, the object of the present invention is attained with an apparatus of the production of an alkanolamine by allowing ammonia to react with an alkylene oxide by use of a microporous material as the catalyst, comprising (a) multiple reactors, all of which have a regenerating unit, and (b) a switching valve which is used to perform the reaction of ammonia with an alkylene oxide in the remaining reactors while the regeneration is being done in at least one of the reactors.
The object of the present invention is attained by a method of regenerating a catalyst for producing an alkanolamine by reaction of ammonia with an alkylene oxide, wherein the catalyst is a microporous material catalyst, and ammonia is passed through the catalyst at 100-350xc2x0 C.
Another object of the present invention is attained by a method of regenerating the catalyst for producing an alkanolamine by treating the catalyst with ozone in a gas phase, in regenerating the microporous material catalyst used for producing an alkanolamine by reaction of ammonia with an alkylene oxide.
In accordance with the present method, since a deactivated catalyst can be regenerated, it can be reused as the catalyst.
In accordance with the present apparatus, since multiple reactors are installed therein, an alkanolamine, particularly a monoalkanolamine and dialkanolamine can be selectively produced while the deactivated catalyst is being regenerated.
In accordance with the present method, since multiple reactors are installed therein and an alkanolamine can be produced while the deactivated catalyst is being regenerated, the production efficiency is high.
In accordance with the present method, since multiple reactors are installed therein, a monoalkanolamine and dialkanolamine can be selectively produced while the deactivated catalyst is being regenerated.
The above and other objects, features and advantages of the present invention will become clear from the following description of the preferred embodiments.